ABB Relion 670 series, Applications Manual

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The following figure shoes typical configuration connections required to utilize this filter in
conjunction with multi-purpose function as non-directional overcurrent protection.
IEC13000179-1-en.vsd
IEC13000179 V1 EN-US
Figure 306: Required ACT configuration
Such overcurrent arrangement can be for example used to achieve the subsynchronous
resonance protection for turbo generators.
12.1.3 Setting guidelines
12.1.3.1 Setting example
GUID-5A3F67BD-7D48-4734-948C-01DAF9470EF8 v2
A relay type used for generator subsynchronous resonance overcurrent protection shall be
replaced. The relay had inverse time operating characteristic as given with the following
formula:
01 op
s
K
t T
I
= +
EQUATION13000029 V1 EN-US
(Equation 549)
Where:
• t
op
is the operating time of the relay
• T
01
is fixed time delay (setting)
• K is a constant (setting)
• I
S
is measured subsynchronous current in primary amperes
The existing relay was applied on a large 50Hz turbo generator which had shaft mechanical
resonance frequency at 18.5Hz. The relay settings were T
01
= 0.64 seconds, K= 35566 Amperes
and minimal subsynchronous current trip level was set at I
S0
=300 Amperes primary.
Solution:
First the IED configuration shall be arranged as shown in Figure 306 . Then the settings for
SMAI HPAC filter and multipurpose function shall be derived from existing relay settings in the
following way:
The subsynchronous current frequency is calculated as follows:
50 18.5 31.5
s
f
Hz Hz Hz
= - =
EQUATION13000030 V1 EN-US
(Equation 550)
Section 12 1MRK 505 343-UEN B
System protection and control
508
Application manual